Although the present description uses a gas turbine engine as an example, it will be understood that the present invention and background of the art encompass any application where a heat exchanger is combined with fluid filters in a compact unit.
In many engines, such as internal combustion engines, and in this example, a gas turbine engine, hydrocarbon fuel is pumped with a fuel pump from a fuel tank into the engine via a fuel line. To remove foreign particles and other impurities, a fuel filter typically is positioned as at an accessible point in the fuel line and optionally a fuel air separator as well. The fuel filter is usually a corrugated fabric cylinder positioned at a location in the engine, which is easily accessed for replacement during routine maintenance.
In a like manner, the oil filter is generally a corrugated fabric cylinder positioned at a conveniently accessible location in the oil distribution system. Lubricating oil is cycled between bearings and an oil reservoir, through an oil pump also positioned at an accessible location for routine maintenance.
In the case of a gas turbine engine, the relatively cool incoming fuel from the fuel tank is often used to cool the relatively hot oil scavenged from the bearings through use of a fuel/oil heat exchanger. The fuel is heated by the oil thereby reducing the risk of icing in the fuel circuit. In a gas turbine engine, the heat exchanger is also positioned at a convenient location for access and inspection at a point along the fuel and oil lines.
It is apparent however, that this collection of separate heat exchanger, oil filter and fuel filter require numerous interconnecting oil and fuel lines all of which are subject to damage or leakage. The cost of installing and maintaining separate components and interconnecting conduits, has in the past being considered to be a necessary feature of complex aircraft engine designs especially. However, even conventional mass-produced automobile engines include separate oil and fuel filters, with accompanying conduits.
It is an object of the invention to reduce the number of engine components, particularly the components related to oil filters, fuel filters and heat exchangers in order to simplify engine design and reduce cost of manufacture, assembly and maintenance.
It is a further object of the invention to combine the heat exchanger and at least one fluid filter to produce a robust combined device, which reduces the risk of leakage and a number of interconnecting fluid pipes in an engine.
It is a further object of the invention to produce a combined heat exchanger and fluid filter, which can be easily adapted to a number of different engine specifications in a simple and straightforward modular manner.
It is further object of the invention to replace conventional stacked plate heat exchangers with an inexpensively produced extruded heat exchanger. Further objects of the invention will be apparent from review of the disclosure and description of the invention below.